1. Field of the Invention
This invention relates to the application of multiple operations in the production of Printed Wired Boards (PWB) or circuit boards which can be accomplished by the usage of a single apparatus. The operations contemplated are:
(a) Exposing a photomask from negative to positive and vice-versa, punching in both at the same time, a number of registration holes for the follow-up production, instead of doing so separately as it is done currently.
(b) Reproducing from a single image photomask a number of stepped-up images forming a bigger photomask, to produce larger quantity of PWB faster.
(c) Exposing with one image photomask a photosensitized panel, stepping the mentioned image photomask by moving the panel longitudinally, without needing to align visually the panel's holes with the photomask's pads as is currently done.
(d) To transport and bring in registration, due to its transporting and pinning technique, a panel's holes with a photomasks pad's centers, in an in-line fashion, from one operation to the next.
(e) Automatically removing a protective foil with vacuum cups after the exposure by holding or pinning technique of the panel which is done by inserting pins from the top into the panel's holes. This technique of clamping the panel to transport it is accomplished by the pins embedded from one end in at least two plates which clamp the panel along its longest side.
2. Description of the Related Technology
The principal step in manufacturing PWB is drilling the hole pattern. The vast majority of producers use numerically controlled, "X" and "Y" coordinates for programming machines which transduce the location of each hole onto a magnetic or code tape. In so doing, each hole's pattern can be electronically stepped and repeated as many times as limited by the panel's size and to each programmed image. To justify or align the working principle of the described apparatus, a hole can be added along its edge as part of the program. As the entire pattern is put on tape, it can be used to drive a drilling machine which, through a series of drilling spindles, repeats exactly what was programmed, except instead of positioning holes on the tape, it drills them on panels of dielectric material, mostly copper cladded. After the panels are drilled and their holes plated through, if desired, their surfaces are sensitized with UV light-sensitive polymer films. Their image, positive and corresponding to the PWB wanted on the photomask from which the drill tape was generated, must be matched, centers to centers, to the drilled holes. Such a matching or registering operation is done visually, but its precision or accuracy is impossible to predict or is very time consuming to achieve due to trials, since the pads and the conductors' line on the photomask are positive, i.e., the images on the photomask are extremely dense black. In order to overcome this problem, the industry developed a diazo film which has orange shaded lines and pads ratehr than black. The orange areas are not transparent to U.V. light but are sufficiently transparent to the eye to see the holes below. This film is expensive and time consuming to produce. Additionally, its transparency starts to break down and UV light penetrates the shaded areas not wanted to be exposed after repeated exposure. Even with such a visual aid, i.e, the diazo film, the matching or registration operation must be done with the holes of the presensitized panels throughout the production lot. This entails the loss of great amounts of time. To increase the registration productivity, most manufacturers punch holes in the photomask with locations corresponding to the extra hole, drilled on the panel and previously programmed. The operation need only insert a pin through the photomask's registration holes and the panel's registration holes to obtain the designed alignment. Separate tools to punch such holes on the photomask or adjustable exposing frames to bring the photomask and the panel's holes into perfect alignment are required.